Re: [PATCH] x86: provide a DMI based port 0x80 I/O delay override

["H. Peter Anvin" <hpa@zytor.com>]

David P. Reed wrote:
> Alan Cox wrote:
> > > Now what's interesting is that the outb to port 80 is *faster* than 
> > > an outb to an unused port, on my machine.  So there's something there 
> > > - actually accepting the bus transaction.   In the ancient 5150 PC, 
> > > 80 was     
> >
> > Yes and I even told you a while back how to verify where it is. From the
> > timing you get its not on the LPC bus but chipset core so pretty
> > certainly an SMM trap as other systems with the same chipset don't have
> > the bug. Probably all that is needed is a BIOS upgrade
> >
> >   
> Actually, I could see whether it was SMM trapping due to AMD MSR's that 
> would allow such trapping, performance or debug registers.  Nothing was 
> set to trap with SMI or other traps on any port outputs.   But I'm 
> continuing to investigate for a cause.  It would be nice if it were a 
> BIOS-fixable problem.  It would be even nicer if the BIOS were GPL...

If it was an SMM trap, I would expect it to be trapped in the SuperIO chip.

	-hpa
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